Help with WEIRD drivetrain noise...

[coheed]

I have done a few searches, but I think I need a little bit better of an explanation than I've found.

Here are my symptoms:

1994 Explorer 4x4 (w/manual hubs)

When I'm on the highway, I get a loud "whining/whurring" noise from the driveline. I can't tell if it's the rear diff or the driveshaft itself, but something along that line. When I let off of the gas it goes away.

BUT... It seems to come back at low speeds (think <15mph) when I'm coasting to like a stop light... I can hear it, but it goes away for the split second that the transmission downshifts into 1st gear (auto tranny).

I see a bunch of info on bearings/pinions/rear-end numbers, and honestly I'm pretty mechanically inclined, I just don't know much about 4wd/rwd.

Thanks in advance for any help or suggestions.
And, just an fyi... Front wheel bearings are brand new, all 4 shocks all the way around are brand new, all 4 brakes all around are brand new. All of that done 50 miles ago...

 

[DeRocha]

Did this noise exist before you did the front end work?

 

[coheed]

Yes it did.

 

[mgmgmg]

I have the same problem with my winter X. It is a bearing in the rear diff. rear pinion bearing which i was told.

 

[coheed]

Can you provide more details? I'd like to fix this, as it doesn't sound very safe...

 

[coheed]

Anyone else have a similar problem?

 

[mgmgmg]

Sry for late reply. It would cost 400-600 to repair..... I was told its a bad bearing that has gotten loose.... Heres my status with my winter X when i first got this problem. It was 5 yrs ago and put almost 30,000 on it since the problem started it hasnt gotten worse or louder?. But my winter X has 252,000 and i only drive it 6 month out of the year with a avg. of 3500 miles.... Thats really all the info i have to give.